VECSEL Spatial Pumping for High-Order HG Mode Generation
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Solution Overview
Problem
Existing laser systems, particularly VECSELs, struggle to generate higher-order Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) modes with controlled and independently changeable transverse mode content, requiring intracavity mode control elements that limit flexibility and output power.
Innovation Solution
A VECSEL-based laser system with multiple spatially-reconfigurable pump channels delivering energy to the gain medium chip, allowing for the generation of high-order HG modes outside the cavity, which can be converted to LG modes using an external astigmatic mode converter, eliminating the need for intracavity optical elements and enabling user-controlled transverse mode content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If intracavity mode control elements are used to generate higher-order HG and LG modes, then transverse mode control is achieved, but output power is reduced and device complexity increases
Solution Approach 1:
The patent extracts the mode control function from the intracavity space and relocates it to external pump channels. By delivering pump energy at spatially varying locations on the gain medium chip surface, the system achieves transverse mode control without placing any control elements inside the laser cavity, thereby avoiding intracavity losses and maintaining high output power.
Solution Approach 2:
The patent applies preliminary spatial modulation to the pump energy distribution before it interacts with the gain medium. By controlling the initial locations where pump energy is delivered on the gain medium chip surface, the system pre-establishes the spatial profile that will determine the resulting transverse mode content of the laser output.
2Adaptability or versatility
If intracavity mode control elements are used to generate higher-order modes, then mode transformation is achieved, but device complexity and size increase
Solution Approach 1:
The patent removes mode control elements from the intracavity space and replaces them with externally controlled pump channels. This extraction eliminates the need for complex intracavity optical components while maintaining the ability to generate and control higher-order HG and LG modes through spatially-resolved optical pumping.
Solution Approach 2:
The patent replaces mechanical or optical mode control elements with a optical pumping scheme. Instead of using physical components inside the cavity to shape modes, the system uses the spatial distribution of pump energy to directly control the transverse mode content, substituting a simpler optical control mechanism for complex mechanical or optical components.
3Adaptability or versatility
If multiple pump channels with spatially-varying initial locations are used, then independent transverse mode generation is achieved, but system complexity increases
Solution Approach 1:
The patent segments the pump energy delivery into multiple independent channels, each capable of targeting specific locations on the gain medium chip surface. This segmentation allows independent control of different transverse modes by directing pump energy to different spatial locations, with each pump channel acting as an independent control element.
Solution Approach 2:
The patent adds a spatial dimension to the pump energy delivery by varying the initial locations on the gain medium chip surface. Instead of uniform pumping, the system exploits the two-dimensional surface of the gain medium to create spatially-resolved pumping patterns that directly correspond to desired transverse mode profiles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves stable, Watt-level output with tunable high-quality laser radiation in various HG and LG modes, offering operational flexibility and efficient conversion between modes without intracavity losses, enabling simultaneous generation of multiple collinearly propagating transverse modes.
Implementation Method 1
multiple pump channels configured to deliver pumping energy to the laser gain medium chip at respectively-corresponding initial locations of a surface of the laser gain medium chip
Implementation Method 2
a laser cavity that is defined by first and second reflectors and has a laser cavity axis. The laser cavity includes a laser gain medium chip that contains the first reflector, while the second reflector is dimensioned to have a center of curvature of the second reflector at an axial point of the first reflector
Implementation Method 3
an astigmatic mode converter (AMC) system disposed outside of the laser cavity on the laser axis
Data Source
AI summary
A vertical external cavity surface emitting laser (VECSEL) based system in a linear single cavity configuration is configured to deliver light in higher-order Hermite-Gaussian transverse modes with Watt-level output power. Simultaneous and independent lasing of spatially-restructurable multiple high-order transverse modes that are collinearly-propagating at the output of such laser cavity is facilitated with the use of an optical pumping scheme devised to control positions of location at which the gain medium of the system is pumped (e.g., locations of focal spots of multiple pump beams on the gain-medium chip). An external astigmatic mode converter is utilized to convert such high-order Hermite-Gaussian modes into corresponding Laguerre-Gaussian modes.